John Garver

Research activity this year was primarily focused on understanding the tectonic evolution of Cretaceous and Paleocene strata in Alaska and California. Building on our field season in the Yakutat area, we were interested in dating rock units, and evaluating provenance of sandstones in the Upper Cretaceous Yakutat Group, which includes a mélange and turbidites. The Yakutat microplate is currently colliding with Alaska, but it has a suspect origin, and we think it correlates to rocks in southern California.
This was a continuation of collaborative work with Cam Davidson at Carleton College, and the last year of our ongoing NSF funded (Tectonics Division) project in Alaska. Thesis work at Union on this Alaska project was done by Alex Dolcimascolo and Julie Sophis (Union, Geology, 2017), and at Carleton by Haley Olson (Carleton Geology, 2017) and Erin Arntson (Carleton, 2018). Alex Dolcimascolo (Union, Geology, 2017) investigated the age and composition of a conglomeratic unit that is part of a mélange unit of uncertain affinity. He did uranium lead dating on zircon from the sandstones and from granite clasts to understand provenance and to aid in stratigraphic correlation to units in the Pacific Northwest. Julie Sophis (Union, Geology, 2017) analyzed detrital zircons from sandstones in the mélange unit and showed that the provenance is remarkably similar to the age correlative Nanaimo Group 1300 km to the south in southern British Columbia.
Actually we think these Alaskan rocks originated in southern California, and thus the Cretaceous shists of California are of interest because they may be correlative. We were lucky to have Alison Horst (Union, Geology, 2017) take on a Keck Project on Schist de Salinas (correlative to Rand-Orocopia-Polona), and therefore her work directly complimented the Alaska effort, because the California rocks and the Alaska rocks may all be related.
In January, Cam Davidson (Carleton College) and I submitted a new NSF tectonics grant proposal entitled Translation and accretion of the Yakutat Microplate and Prince William terrane, Alaska. This proposed new work builds on nearly a decade of work in the southern tier of Alaska. In early July we were delighted to receive news from the NSF that the proposal was funded, so we will soon initiate four more years of Alaskan tectonic studies that will provide important field and thesis opportunities for Union students.
We continue to have projects aimed at understanding radiation damage in zircon, and how damage drives internal disorder and crystal disintegration. This work has important implications for geochronology, and have continued work on the uranium distribution and radioactivity of the Devonian Lucerne and Tunk Lake Plutons. Radiation damage leads to uranium loss and redistribution that results in an important health hazard in Maine because these zircon produce radon, which causes lung cancer.
In March 2017, Jackie Cockburn (University of Guelph) and I were again co-chairs for the Mohawk Watershed Symposium at Union (this was the 9th annual), which was well attended by both professionals and students. In the next several years we should see a greater oversight in the Mohawk watershed, which will enhance recreational opportunities, and develop a mechanism for better oversight of our water resources. Next year we look forward to the tenth consecutive watershed symposium.
I am on sabbatical this year, and the first thing that Jacquie and I did was take a long-planned and anticipated trip to Iceland. The photo above is from Jökulsárlón, a glacial lagoon, bordering Vatnajökull National Park in southern Iceland.

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